Electric circuit interrupter



April 3, 1934. H, PEARCE 1,953,820

ELECTRIC CIRCUIT INTERRUPTER Filfid April 5, 1932 Inventor: Herbert Pearc 2:,

His Attorney.

Patented Apr. 3, 1934 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT INTERRUPTER New York Application April 5, 1932, Serial No. 603,392

In Great Britain April 20, 1931 5 Claims.

This invention relates to electric circuit interrupters of the kind in which the interruption in the circuit is arranged to occur within a body of insulating liquid, hereinafter for convenience referred to as oil.

In circuit breakers of the aforesaid type it has been proposed to arrange the contact surfaces between which the break occurs when the circuit is interrupted within a chamber, usually referred to as an explosion pot, said chamber or pot being immersed in the general body of oil in the circuit interrupter tank. Where more than one break as a double break, is to be made by the circuit opening operation each break is arranged to occur in a separate explosion pot. The explosion pots are provided with vents so that an oil jet is directed through the arc by reason of the pressure generated by the are formed on separation of the contact surfaces.

According to the present invention a double break circuit interrupter is provided with a substantially continuous chamber forming two explosion pots, one for each break, immersed in the body of oil in a tank, said explosion pots being interconnected by means of a tube and an aperture being provided in one of the explosion pots immediately opposite the place where the connecting tube enters said pot. The effect of this arrangement is that the pressure set up by the two arcs formed between the contact surfaces at each break will cause a movement or blast of oil through the are at the throat of each explosion pot and also, where provided, through the additional opening in the explosion pot. Under influence of arcing pressure there will be a movement of oil along the connecting tube towards the last mentioned explosion pot and this movement will assist in filling the space between the arcing contacts in this pot with an insulating material of high dielectric strength which may be oil or gas, or a mixture of the two, thus tending to rupture the arc.

In applying the invention to high voltage circuits where longer arcs are involved the connecting tube may be divided into a number of separate portions so that a plurality of passages are formed connecting one explosion pot with the other. The separate passages and the explosion pots into which they open may be considered as together forming a series of separate single cells or chambers, each cell being closed at one end and open at the other. The cells may conveniently open into the main body of oil in the tank at alternate ends.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to 6 and forming a part of this specification.

Referring to the drawing, Figs. 1 and 2 are end elevation and side elevation views, partly in section, respectively, of one phase of a multiphase circuit breaker and Fig. 3 shows a modified arrangement for high voltage circuits.

Referring to the arrangement shown in Figs. 1 and 2, a substantially rectangular horizontal chamber 1 is suitably formed as by means of two plates 2 and 3 of insulating material bent to an inverted channel cross-section as shown in Fig. 2, and secured together as by means of bolts. One end of the chamber is closed by a block 4 of wood or other insulating material and the other end is open, the block 5 serving as a spacing piece against which the depending sides of the plates 2 and 3 may be clamped. The chamber 1 constitutes two explosion pots connected together by a passage, one of which pots is vented at 1' to the main oil body.

Projecting through apertures in the horizontal surface of the upper plate 2 are two stationary contacts 6 and '7 with which are associated a pair of movable contacts 8 and 9. These two moving contacts are connected together at their lower ends by means of a bar 10 of flexible conducting material forming a bridging member and are resiliently held against the fixed contacts 6 and '7 in the closed position of the circuit interrupter as by means of springs 19 mounted on a bridge piece 12. The movable contacts pass through apertures or throats l3 and 14 in the lower plate 3, the clearance at the throat 13 preferably being slightly greater than that at the throat 14. The bridge piece 12 which serves to actuate the moving contacts 8 and 9 is operated by means of the lift rod 15 which passes with slight clearance through aperatures in the horizontal portions of the plates 2 and 3.

The explosion chamber and contact arrangement above described is submerged in a tank 16' which is provided with a lining 17 of insulating material and is filled with oil or other suitable insulating liqud. The tank accommodates the circuit interrupters for all the different phases, these interrupters being separated from one another by insulating partitions 18.

When the lift rod 15 is lowered from the position shown in Fig. 1 to effect opening of the circuit, separation of the coacting contacts 6, 8 and 7, 9 results in arcing at said contacts and the consequent generation oi pressure in the insulating liquid surrounding said contacts. During the initial part of the circuit opening movement when the contact 9 is still within the aperture 14, the 5 pressure generated by arcing at the contacts 6, 8 is effective to drive a cross blast of oil through the are at the contacts 7, 9 to exhaust through the opening 1'. Upon continued lowering of the 10 bridging member 12, the pressure within the wardly through the apertures 13 and 14 through the respective arcs in the event that the circuit has not been interrupted by the aforesaid cross blast.

In a somewhat modified form of the above arrangement, the channel section plates 2 and 3 may be made wide enough to extend on one side to the insulating lining 17 of the tank 16 and on the other side to the insulating partition 18, clearance being suflicient only to allow the tank to be raised and lowered easily. In this modifica- 'tion, the block of wood a is made of suificient width to extend also to the insulating lining 17 of the tank. Alternatively, to increase the width of the plates 2 and 3, blocks of wood or other insulating material of suitable thickness may be secured to the depending sides of the plates 2 and 3.

With the above arrangement, the arc interrupting portion of the circuit breaker is entirely sealed off from the rest of the oil tank 16 except for the opening 1' at the right hand end (Fig. 1) between the plates 2 and 3. This opening allows communication with the space above the arc chamber so that a blast of oil acrossthe are between the contacts 7 and 9 is thus obtained. The clearance between the structure and the tank necessary to allow the latter to be raised and lowered will prevent excessive pressures in the are breaking chamber.

Referring to the high tension interrupter shown in Fig. 3, three comparatively shallow horizontal explosion chambers 1, 11 and 21 which are rectangular in cross-section are formed by four horizontal plates 2, 3, 22 and 23 respectively of insulating material, which are immersed in oil in a tank 16 having a lining 1'7 of insulating material.

The plates are spaced apart and the sides of the chambers are suitably closed by insulating material. In this particular arrangement the chambers 1 and 21 are closed at corresponding ends and the chamber 11 at the opposite end by blocks 20 of insulating material so as to provide alternate openings at the ends of the chambers. Alternatively, the chambers 1, 11 and 21 may all be closed at the same end by the blocks 20.

Depending through apertures in the top plate 2 are two fixed contacts 6 and '7 with which oooperate in the manner previously mentioned moving contacts 8 and 9 of the double break circuit interrupter. The moving contacts 8 and 9 are resiliently mounted in a bridging member 12 as Y 'The breaks between the contacts 6 and 7 and 8 chamber 1 also expels the insulating liquid down and 9 will thus occur at each end of the rectangular chambers 1, 11 and 21 and each of the two arcs in any one phase will be subject to interrupting action by the oil blast at successive points in its length. The openings at alternate ends of the explosion chambers allow oil blasts alternately at opposite ends into the main body of oil in the tank 16 and the multiplicity of vents of the explosion chambers avoids excessively high pressures which are set up if a single explosion pot is used on each break.

In the aforesaid arrangements the explosion pots may be made entirely of suitable insulating material or of insulated metal. In carrying out the invention the explosion pots may be made shorter, of small diameter and have larger clearances at the throat than is the case with constructions heretofore adopted where the pots were not connected, and in such case the pressures set up in the explosion pots will be much less than those obtained'with the ordinary construction.

It should be understood that my invention is 'not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A circuit interrupter of the fluid-break type comprising relatively movable contacts forming two breaks in series, an insulating casing forming 'a substantially continuous explosion chamber for said breaks, said casing having a blast-exhaust aperture venting said chamber, the movable contacts extending into said chamber through apertures in said casing, and actuating means for opening and withdrawin the movable contacts from said chamber.

2. A circuit interrupter of the fluid-break type comprising contact structure including a pair of stationary contacts and a coacting bridging member immersed in an insulating liquid, an insulating casing forming an explosion chamber for each pair of coacting contacts, said casing having a horizontal passage interconnecting said chambers and terminating in a vent for one of said chambers, the lower wall of said casing having apertures for receiving the coacting bridge contacts, and means for lowering said bridgingAZS member and interrupting the circuit.

3. A circuit interrupter of the fluid-break type comprising contact structure including a pair of stationary contacts and a movable bridging member coacting therewith immersed in an inl30 sulating liquid, an insulating casing forming a chamber common to said coacting contacts and vented adjacent one of said pairs of contacts comprising a pair of channel-shaped insulating members having depending sides, one of said/ members secured with respect to said stationary contacts and enclosing the same, and the other of said members forming with said first member a chamber common to the pairs of coacting contacts, said chamber being open at one;-l40 end thereof, and an insulating block secured to and closing said channel members at the opposite end.

4. A circuit interrupter of the fluid-break type comprising contact structure including a pair of' stationary contacts and a coacting bridging member immersed in an insulating liquid, and insulating structure secured with respect to said stationary contacts forming a plurality of horizontally arranged passages each common to thef breaks at the aforesaid coacting contacts and exhausting at the sides of said casing, said casing:

having apertures transversely of and connected.

with said passages for receiving the movable:

bridging member.

5. A circuit interrupter of the fluid-break type comprising a pair of stationary contacts, a bridging member coacting therewith, and a casing comprising a plurality of plates of insulating HERBERT PEARCE 

